An Iranian journalist who was reporting on the Iranian nuclear talks in Switzerland has applied for political asylum, the Iranian Foreign Ministry said.

The journalist, Amir Hossein Motaghi, worked as a top media aide for President Hassan Rouhani during his 2013 election campaign and had travelled to Lausanne to report on nuclear talks for the Iran Student Correspondents Association (ISCA).

However, he was sacked on 24 March after his bosses learned of his defection, a ministry statement said.

After his defection, Motaghi spoke to foreign media about sensitive political issues, an act deemed unacceptable for reporters working in Iranian media.

Speaking to a London-based opposition TV channel, Motaghi said that he no longer saw any “sense” to his role as a journalist and editor because he only wrote what he was told to by the authorities.

“There are a number of people attending on the Iranian side at the negotiations who are said to be journalists reporting on the negotiations,” he told Irane Farda television. “But they are not journalists and their main job is to make sure that all the news fed back to Iran goes through their channels.”

While Rouhani is seen as a reformer in Iran, all presidential candidates must be approved by the Supreme Leader Ali Khamenei. Since Rouhani took power in 2013, press freedoms in Iran have barely improved. According to Reporters Without Borders' World Press Freedom Index, the country came in 173rd place globally out of 180 countries in terms of press freedom, with only Vietnam, China, Somalia, Syria, Turkmenistan, the Democratic Republic of Congo and Eritrea faring worse.

Motaghi has repeatedly posted about sensitive issues on his Instagram account, including a picture of Jason Rezaian, the Washington Post's correspondent in Iran, who was jailed in July last year and is facing trial on unspecified charges.

Motaghi also put a picture of Rezaian's wife, Yeganeh Salehi, on his Instagram page. Salehi was arrested at the same time as Rezaian but she was bailed in October. She has not worked as a journalist since.

"I hope they will be released soon," Motaghi wrote in the caption to the picture he posted eight months ago.

Iranians are watching the talks in Lausanne closely, where foreign ministers from Iran, the United States, China, Russia, Britain, France and Germany hope to strike a deal over the Islamic republic's disputed nuclear programme by midnight on Tuesday.